Apparatus, system and method for mobile communication

ABSTRACT

In order for making MTC more efficient and/or secure, a base station forming a communication system connects a UE to a core network. A node serves as an entering point to the core network for a service provider, and transmits traffic between the service provider and the UE. The node establishes, as a connection to the base station, a first connection for directly transceiving messages between the node and the base station. Alternatively, the node establishes a second connection for transparently transceiving the messages through a different node that is placed within the core network and has established a different secure connection to the base station.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/287,806, filed Feb. 27, 2019; which is a continuation of U.S.application Ser. No. 15/808,515, filed Nov. 9, 2017; which is acontinuation of U.S. application Ser. No. 15/032,847, filed Apr. 28,2016; which is a National Stage Entry of International Application No.PCT/JP2014/005332, filed Oct. 21, 2014; which is based upon and claimsthe benefit of priority from Japanese patent application No.2013-226680, filed on Oct. 31, 2013; the disclosures of all of which areincorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to an apparatus, a system and a method forMTC (Machine-Type-Communication), and particularly to an interfacebetween a base station and a core network node.

BACKGROUND ART

MTC brings very different characteristics to the current mobilecommunications system such as extremely power constrained, mostly verylow data-rate, intermittent data, very large number of devices andgenerally low mobility. The SAE (System Architecture Evolution)/LTE(Long Term Evolution) system can be optimized for these MTCcharacteristics and thus architecture enhancements may be needed whichcan 1) cater for the MTC characteristics, while 2) minimizing impact oncurrent network is needed.

Note that the architecture of MTC has been studied in NPLs 1 and 2, forexample.

CITATION LIST Non Patent Literature

-   NPL 1: 3GPP TR 33.868, “Security aspects of Machine-Type and other    Mobile Data Applications Communications Enhancements; (Release 12)”,    V0.15.0, 2013-09, Clauses 5.1 and 5.7, pp. 13-30 and 67-104-   NPL 2: 3GPP TR 23.887, “Machine-Type and other mobile data    applications Communications enhancements (Release 12)”, V1.2.0,    2013-08, Clause 5.1.1.3.3, pp. 25-32

SUMMARY OF INVENTION Technical Problem

However, the inventors of this application have found that there areproblems in current proposed solutions for T5 interface based devicetriggering and SDT (small data transmission) in 3GPP (3rd GenerationPartnership Project). For example, the messages for device triggeringand SDT will be concentrated in very limited number of nodes e.g. theMME (Mobility Management Entity). This could lead to various attacks tothe nodes or cause overload to the nodes such that they are not able tofulfill all requests. Note that the device triggering and the small dataare the messages in small size, and the interface T5 is a referencepoint which resides between the MME and an MTC-IWF (MTC Inter-WorkingFunction).

In current T5 based solution, the small data are carried in NAS(Non-Access Stratum) message and it relies on NAS security, which hasthe following impact to the system.

1) It will increase the load to NAS layer and to MME for securityprocessing.

2) It causes NAS COUNT wrap around issue in which the AKA(Authentication and Key Agreement) procedure will be performed tonegotiate new NAS keys. This may also lead loading to HSS (HomeSubscriber Server).

3) Since the current authorization on SCS (Service Capability Server) isnot enough (for example there no check on frequency of sending SD (SmallData), no check on whether normal data is sent as small data), DL(Downlink) NAS message now is triggered by SCS. This is to open MME tointernet and cause attack to the network element.

Accordingly, an exemplary object of the present invention is to providea solution for making MTC more efficient and/or secure.

Solution to Problem

In order to achieve the above-mentioned object, a node according tofirst exemplary aspect of the present invention serves as an enteringpoint to a core network for a service provider. This node includes:establishment means for establishing a connection to a base station; andtransmission means for transmitting, by use of the connection, trafficbetween the service provider and a UE (User Equipment) that attaches tothe core network through the base station. The establishment means isconfigured to establish as the connection: a first connection fordirectly transceiving messages between the node and the base station; ora second connection for transparently transceiving the messages througha different node that is placed within the core network and hasestablished a different secure connection to the base station.

Further, a node according to second exemplary aspect of the presentinvention manages mobility of a UE attaching to a core network through abase station. This node includes: transfer means for transparentlytransferring messages between the base station and a different node, thedifferent node serving as an entering point to the core network for aservice provider and transmitting traffic between the service providerand the UE.

Further, a node according to third exemplary aspect of the presentinvention manages subscription information on a UE attaching to a corenetwork through a base station. This node includes: request means forrequesting information on the base station from a first node thatmanages mobility of the UE; and send means for sending the informationto a second node that serves as an entering point to the core networkfor a service provider and that transmits traffic between the serviceprovider and the UE.

Further, a base station according to fourth exemplary aspect of thepresent invention includes: transceiving means for transceiving messagesbetween the base station and a node through a first connection or asecond connection to the node, the node serving as an entering point toa core network for a service provider and transmitting traffic betweenthe service provider and a UE that attaches to the core network throughthe base station, the first connection being for directly transceivingthe messages, the second connection being for transparently transceivingthe messages through a different node that is placed within the corenetwork and has established a different secure connection to the basestation.

Further, a UE according to fifth exemplary aspect of the presentinvention attaches to a core network through a base station and thatcommunicates with a service provider. This UE includes: send means forsending, on a radio bearer shared with one or more different UEs, to thebase station a message to be transmitted to the service provider throughthe core network.

Further, a communication system according to sixth exemplary aspect ofthe present invention includes: a base station that connects a UE to acore network; and a node that serves as an entering point to the corenetwork for a service provider and that transmits traffic between theservice provider and the UE. The node establishes as a connection to thebase station: a first connection for directly transceiving messagesbetween the node and the base station; or a second connection fortransparently transceiving the messages through a different node that isplaced within the core network and has established a different secureconnection to the base station.

Further, a method according to seventh exemplary aspect of the presentinvention provides a method of controlling operation in a node thatserves as an entering point to a core network for a service provider.This method includes: establishing a connection to a base station; andtransmitting, by use of the connection, traffic between the serviceprovider and a UE that attaches to the core network through the basestation. As the connection, one of following connections is established:a first connection for directly transceiving messages between the nodeand the base station; or a second connection for transparentlytransceiving the messages through a different node that is placed withinthe core network and has established a different secure connection tothe base station.

Further, a method according to eighth exemplary aspect of the presentinvention provides a method of controlling operations in a node thatmanages mobility of a UE attaching to a core network through a basestation. This method includes: transparently transferring messagesbetween the base station and a different node, the different nodeserving as an entering point to the core network for a service providerand transmitting traffic between the service provider and the UE.

Further, a method according to ninth exemplary aspect of the presentinvention provides a method of controlling operations in a node thatmanages subscription information on a UE attaching to a core networkthrough a base station. This method includes: requesting information onthe base station from a first node that manages mobility of the UE; andsending the information to a second node that serves as an enteringpoint to the core network for a service provider and that transmitstraffic between the service provider and the UE.

Further, a method according to tenth exemplary aspect of the presentinvention provides a method of controlling operations in a base station.This method includes: transceiving messages between the base station anda node through a first connection or a second connection to the node,the node serving as an entering point to a core network for a serviceprovider and transmitting traffic between the service provider and a UEthat attaches to the core network through the base station, the firstconnection being for directly transceiving the messages, the secondconnection being for transparently transceiving the messages through adifferent node that is placed within the core network and hasestablished a different secure connection to the base station.

Further, a method according to eleventh exemplary aspect of the presentinvention provides a method of controlling operations in a UE thatattaches to a core network through a base station and that communicateswith a service provider. This method includes: sending, on a radiobearer shared with one or more different UEs, to the base station amessage to be transmitted to the service provider through the corenetwork.

Further, a method according to twelfth exemplary aspect of the presentinvention provides a method of establishing security association in amobile communication system including a UE (User Equipment) and anMTC-IWF (Machine-Type-Communication Inter-Working Function). This methodincludes: providing by a protocol between the UE and the MTC-IWF,ciphering, deciphering, integrity protection and integrity verification;and including a key identifier of subkeys for the UE and the MTC-IWF ina packet format of the protocol. The key identifier determines thesubkeys to be used for small data transmission protection or triggermessage transmission protection.

Further, a mobile communication system according to thirteenth exemplaryaspect of the present invention includes: a UE (User Equipment); and anMTC-IWF (Machine-Type-Communication Inter-Working Function). A protocolbetween the UE and the MTC-IWF provides ciphering, deciphering,integrity protection and integrity verification. A packet format of theprotocol includes a key identifier of subkeys for the UE and theMTC-IWF. The key identifier determines the subkeys to be used for smalldata transmission protection or trigger message transmission protection.

Further, an MTC-IWF (Machine-Type-Communication Inter-Working Function)according to fourteenth exemplary aspect of the present inventionincludes: first means for connecting with a UE (user equipment) via abase station; and second means for performing authorization on the UEand an SCS (Service Capability Server). A protocol between the UE andthe MTC-IWF provides ciphering, deciphering, integrity protection andintegrity verification. A packet format of the protocol includes a keyidentifier of subkeys for the UE and the MTC-IWF. The key identifierdetermines the subkeys to be used for small data transmission protectionor trigger message transmission protection.

Furthermore, a UE (User Equipment) according to fifteenth exemplaryaspect of the present invention establishes security association with anMTC-IWF (Machine-Type-Communication Inter-Working Function) in a mobilecommunication system. This UE includes: first means for sending smalldata to an SCS (Service Capability Server) or receiving small data or atrigger message from the SCS via the MTC-IWF; and second means forsharing a key and subkeys with the MTC-IWF for confidentiality andintegrity protection. A protocol between the UE and the MTC-IWF providesciphering, deciphering, integrity protection and integrity verification.A packet format of the protocol includes a key identifier of subkeys forthe UE and the MTC-IWF. The key identifier determines the subkeys to beused for small data transmission protection or trigger messagetransmission protection.

Advantageous Effects of Invention

According to the present invention, it is possible to solve theabove-mentioned problems, and thus to provide a solution for making MTCmore efficient and/or secure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a first configuration example ofcommunication systems according to an exemplary embodiment of thepresent invention.

FIG. 2 is a block diagram showing a second configuration example of thecommunication systems according to the exemplary embodiment.

FIG. 3 is a block diagram showing a third configuration example of thecommunication systems according to the exemplary embodiment.

FIG. 4 is a block diagram showing examples of connections establishedbetween a first node and a base station according to the exemplaryembodiment.

FIG. 5 is a block diagram showing an example of protocol stacks used forthe communication systems according to the exemplary embodiment.

FIG. 6 is a block diagram showing another example of the protocol stacksused for the communication systems according to the exemplaryembodiment.

FIG. 7 is a sequence diagram showing a first example of operations inthe communication systems according to the exemplary embodiment.

FIG. 8 is a sequence diagram showing a second example of the operationsin the communication systems according to the exemplary embodiment.

FIG. 9 is a sequence diagram showing a third example of the operationsin the communication systems according to the exemplary embodiment.

FIG. 10 is a sequence diagram showing a fourth example of the operationsin the communication systems according to the exemplary embodiment.

FIG. 11 is a block diagram showing a configuration example of the firstnode according to the exemplary embodiment.

FIG. 12 is a block diagram showing a configuration example of a secondnode according to the exemplary embodiment.

FIG. 13 is a block diagram showing a configuration example of a thirdnode according to the exemplary embodiment.

FIG. 14 is a block diagram showing a configuration example of the basestation according to the exemplary embodiment.

FIG. 15 is a block diagram showing a configuration example of a UEaccording to the exemplary embodiment.

FIG. 16 is a block diagram showing a protocol stack between a UE and anMTC-IWF, which will be proposed to 3GPP based on the present invention.

FIG. 17 is a block diagram showing a packet format which will beproposed to 3GPP based on the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an exemplary embodiment of nodes, a base station and a UEaccording to the present invention, and communication systems to whichthese nodes, base station and UE are applied, will be described with theaccompany drawings.

This exemplary embodiment considers a UE subscribing to MTC (M2M(Machine-to-Machine)) service, but the present invention is not limitedto MTC (M2M) type of application.

1. New Interface T6:

This exemplary embodiment proposes a direct interface between an MTC-IWFand an eNB (evolved Node B), named T6. This interface is for secure andefficient MTC communication and it supports both CP (Control Plane) andUP (User Plane). Idea is to use the MTC-IWF as the end point in a mobilenetwork for interconnection with a service provider, and can achieve thefollowing advantageous effects (A) to (G), for example.

(A) Offload MME burden caused by the large number of devicescommunication in case of T5 triggering and small data delivery.

(B) Offload MME burden caused by the processing for NAS security in caseof T5 triggering and small data delivery.

(C) Prevent DoS (Denial-of-Service) attack to network element and UEfrom SCS side.

(D) Prevent DoS attack to network element and SCS from UE side.

(E) Trigger and small data transmission can be independent from NASsecurity.

(F) MTC-IWF as center point of MTC communication means that UE can alsoconnect over WiFi or any other network element which has interface withMTC-IWF, without any modification.

(G) MTC-IWF can take care of all issues related to MTC being discussedin 3GPP.

For a given UE, the MTC-IWF can find the serving eNB indirectly byobtaining the serving eNB information from MME via HSS, or directly fromMME. MTC trigger and small data are delivered over the T6 interface.MTC-IWF and UE establish a security association, and the trigger andsmall data are protected with keys shared between UE and MTC-IWF.

As an option, MTC-IWF can send the integrity session key it shares withUE to eNB, and thus eNB can perform authorization at an early stage toprevent DoS attack from UEs to network.

FIGS. 1 to 3 show the architecture with new interface T6.

FIG. 1 shows a configuration example of a communication system fornon-roaming case.

As shown in FIG. 1, this communication system includes one or more UEs10, one or more eNB 20, a core network, and an SCS 60. The core networkincludes, as its network nodes, an MME 30, an HSS 40, and an MTC-IFW 50.Note that although the illustration is omitted, the core network alsoincludes, as other network nodes, an SGSN (Serving GPRS (General PacketRadio Service) Support Node), an MSC (Mobile Switching Centre) and thelike. The SGSN and the MSC function as with the MME 30.

The UE 10 attaches to the MME 30 through the eNB 20, therebycommunicating with the SCS 60 through the core network. Messages betweenthe UE 10 and the eNB 20 can be carried on AS (Access Stratum) security.Messages between the UE 10 and the MME 30 can be carried on NASsecurity. Note that the UE 10 is a UE equipped for MTC, which will besometimes referred to as “MTC UE” or “MTC device” in the followingdescription.

The eNB 20 forms a RAN (Radio Access Network), thereby connecting the UE10 to the core network. As mentioned above, messages between the eNB 20and the MTC-IWF 50 can be carried over the interface T6. Messagesbetween the eNB 20 and the MME 30 can be carried over an interface 51.

The MME 30 manages mobility of the UE 10. Messages between the MME 30and the HSS 40 are carried over an interface S6a. Messages between theMME 30 and the MTC-IWF 50 can be carried over the interface T5.

The HSS 40 manages subscription information on the UE 10. Messagesbetween the HSS 40 and the MTC-IWF 50 are carried over an interface S6m.

The MTC-IWF 50 serves as an entering point to the core network for theSCS 60. Messages between the MTC-IWF 50 and the SCS 60 are carried overan interface Tsp. Upon transmitting traffic between the UE 10 and theSCS 60, the MTC-IWF uses the interface T6.

The SCS 60 connects to the core network to communicate with the UE 10.The UE 10 can host one or multiple MTC Applications. The correspondingMTC Applications in the external network are hosted on the SCS 60.

On the other hand, there are two options of network architecture inroaming case.

As shown in FIG. 2, in a case where there is no MTC-IWF in VPLMN(Visited PLMN (Public Land Mobile Network)), an H-MTC-IWF (Home MTC-IWF)50H connects to the eNB 20 via an interface T6′.

As shown in FIG. 3, in a case where there is a MTC-IWF in VPLMN(V-MTC-IWF), the H-MTC-IWF 50H connects to a V-MTC-IWF 50V via aninterface Tiw. As with the MTC-IWF 50 shown in FIG. 1, the V-MTC-IWF 50Vconnects to the eNB 20 via the interface T6, and connects to the MME 30via the interface T5.

2. Protocol Stack and Message Flow:

FIG. 4 shows message flow in case of non-roaming. The end-points in 3GPPnetwork for small data and device trigger are UE and MTC-IWF.

There are two ways to transmit the messages carrying small data anddevice trigger by:

1) using the direct interface T6 between the eNB 20 and the MTC-IWF 50,as shown by dotted lines in FIG. 4; and

2) using the virtual interface T6, as shown by dashed-dotted lines inFIG. 4.

In the way 2), the SDDTE (Small Data and Device Triggering Enhancements)protocol is carried hop-by-hop. The eNB 20 and the MME 30 verify whetherthere is a higher layer protocol (i.e. SDDTE) carrying SD incase themessage is carrying SD, they only forward the message but do not performany process for NAS and AS security.

FIG. 5 shows the proposed protocol stack with using the directinterface. Meanwhile, FIG. 6 shows the proposed protocol stack withusing the virtual interface. The protocol SDDTE spans between the UE 10and the MTC-IWF 50, and can be transparent to the MME/SGSN 30.

As shown in FIG. 5, when the interface T6 is a direct interface betweenthe eNB 20 and the MTC-IWF 50, the small data and device trigger aretransmitted over it directly, and over LTE-Uu between the eNB 20 and theUE 10.

As shown in FIG. 6, when the interface T6 is a virtual interface, thesmall data and derive trigger are transmitted hop-by-hop over T5, S1-MMEand LTE-Uu. In comparison with T5 solution, in this exemplaryembodiment, when the eNB 20 and the MME 30 verify there is an upperprotocol (SDDTE) carrying SD, it only forwards the messages between theMTC-IWF 50 and the eNB 20.

New things here:

-   -   Modification on the RRC (Radio Resource Control) at LTE-Uu        interface and S1-AP at S1-MME interface for SDDTE transmission;        and    -   Messages that are sent over T6, which will be given in next        section.

Note that the description as to the interface T6 in this section issimilarly applied to the interface T6′ shown in FIG. 2 and the interfaceT6 between the eNB 20 and the V-MTC-IWF 50V shown in FIG. 3.

Next, operation examples of this exemplary embodiment will be describedin detail with reference to FIGS. 7 to 10. Note that configurationexamples of the MTC-IWF 50, the MME 30, the HSS 40, the eNB 20, and theUE 10 will be described later with reference to FIGS. 11 to 15.

3. Device Trigger and Small Data Transmission:

In this section, message flows of MTC device trigger and Small DataTransmission will be described.

3.1. MTC Device Trigger:

FIG. 7 shows the trigger delivery flow. Steps S15 and S17 are newmessages using the T6 interface. Moreover, messages shown at steps S13and S14 are also modified from the existing messages defined in 3GPP.

As shown in FIG. 7, the SCS 60 sends a Device Trigger Request to theMTC-IWF 50 (step S11).

The MTC-IWF 50 performs authorization (step S12). When the MTC-IWF 50does not have subscriber and serving node information, for example, whenthe MTC-IWF 50 receives request to the UE 10 for the first time, theMTC-IWF 50 will request the HSS 40 for them (step S13).

Specifically, the MTC-IWF 50 requests to the HSS 40 of the target devicesubscriber information (step S13_1). The HSS 40 sends a Serving NodeInformation Request to the MME 30 (step S13_2). The MME 30 can be thelast MME that the UE 10 attached to. The MME 30 responds with a ServingNode Information Response (step S13_3). The MME 30 provides the currenteNB information to the HSS 40. The HSS 40 sends a Subscriber InformationResponse with serving node information to the MTC-IWF 50 (step S13_4).

Alternatively or in addition, the MME 30 sends a Serving NodeInformation Update message to the MTC-IWF 50 each time the serving eNBis changed (step S14_1). The proposed solution is therefore mosteffective for low mobility MTC UEs.

The MTC-IWF 50 submits the Trigger to the current serving eNB 20 overthe interface T6 (step S15).

The eNB 20 pages the UE 10 locally without MME involvement and transfersthe message to the UE 10 (step S16). The UE 10 may also respond with Ack(Acknowledgement) message.

The eNB 20 sends a Submit Trigger Confirm message to the MTC-IWF 50 overthe interface T6 (step S17).

The MTC-IWF 50 sends the Device Trigger confirm message to the SCS 60(step S18).

3.2. MT Small Data Transmission:

FIG. 8 shows the MT (Mobile Terminated) Small data transmission flow.The MTC-IWF 50 triggers the MME 30 to use normal Paging procedure withindication of small data to inform there will be a small data. When theMTC-IWF 50 receives a response of Paging, the MTC-IWF 50 sends the smalldata over interface T6. Steps S24, S28, S29 and S33 are new messages.

As shown in FIG. 8, the SCS 60 sends a Small Data Submission Request tothe MTC-IWF 50 (step S21).

The MTC-IWF 50 performs authorization on the SCS 60 and the UE 10 (stepS22). Upon a successful authorization, the MTC-IWF 50 retrieves theserving node information, from the HSS 40 or directly from the MME 30.Alternatively, the MME 30 sends the Serving Node Information Update tothe MTC-IWF 50 each time the serving eNB is changed (step S23).

The MTC-IWF 50 sends a Request Paging message to the MME 30 with UE IDand msg=“small data” to inform the UE 10 that small data will bedelivered to it (step S24). Alternatively, the MTC-IWF 50 submits thesmall data directly to the eNB 20 at step S29, and skips the followingsteps S24 to S28 in between. In this case, the eNB 20 performs a localpaging of the MTC UE 10 without involving the MME 30 before forwardingthe small data to the UE 10. This would be more effective especially forlow mobility MTC UEs.

The MME 30 sends the Request Paging message to the eNB 20 (step S25).

The eNB 20 sends the Paging message to the UE 10 (step S26).

The UE 10 responds to the Paging from the MME 30 with a Service Requestmessage (step S27).

The MME 30 sends a Response Paging message with UE ID and the eNBaddress to the MTC-IWF 50 (step S28). This will indicate the MTC-IWF 50that the MME 30 has paged the UE 10 and received a response, and thusthe MTC-IWF 50 can send the small data directly to the eNB 20.

The MTC-IWF 50 sends the small data to the eNB 20 with target UE ID,indicator of msg=“small data”, with integrity protection by the keyshared between the UE 10 and the MTC-IWF 50 (step S29).

The eNB 20 forwards the Small Data to the UE 10 (step S30).

If the indicator shows msg=“small data”, the UE 10 performs integritycheck with the key it shares with the MTC-IWF 50 (step S31).

The UE 10 sends a confirm of receiving the Small Data if the integritycheck was successful at previous step S31 (step S32).

The eNB 20 forwards the submit small data confirm to the MTC-IWF 50(step S33).

The MTC-IWF 50 forwards the submit confirm to the SCS 60 (step S34).

3.3. MO Small Data Transmission:

FIG. 9 shows the MO (Mobile Originated) Small data transmission flow.Step S44, S48 and S50 are new messages using the interface T6. A messageshown at step S43 is also new.

As shown in FIG. 9, the UE 10 sends a Small Data Submission Request withintegrity and/or confidentiality protection by the key it shares withthe MTC-IWF 50 (step S41).

The request message is sent on SRB0 (Signalling Radio Bearer 0, asdefined in 3GPP 36.331), and it contains SCS ID. There is no need toestablish RRC connection between the UE 10 and the eNB 20, so that RRCsignaling can be reduced.

The eNB 20 will skip AS integrity check if the msg=“small data” (stepS42).

The eNB 20 retrieves routing information from the MME 30, of whichMTC-IWF to communicate with (step S43).

Then, the eNB 20 forwards the small data to the MTC-IWF 50 (step S44).

The MTC-IWF 50 performs integrity check, with the key it shares with theUE 10 (step S45). If the integrity check is successful, the MTC-IWF 50delivers small data to the SCS 60 (step S46).

The SCS 60 responds Small data confirm to the MTC-IWF 50 (step S47).

The MTC-IWF 50 forwards the Small data confirm to the eNB 20 (step S48).

The eNB 20 forwards the Small data confirm to the UE 10 (step S49).

If the integrity check fails at above Step S6, the MTC-IWF 50 sendsSmall Data Reject to the UE 10 (step S50).

3.4. T6 Connection Release:

If the T6 connection has not been active for a given time then it can bereleased. The T6 connection release procedure is given in FIG. 10.

As shown in FIG. 10, a T6 connection release timer expires at theMTC-IWF 50 (step S61).

At this time, the MTC-IWF 50 indicates the eNB 20 to release the T6Connection (step S62). When the T6 connection is released, the eNB 20removes related information for small data and device trigger. Note thatthis procedure is also applied to the MME 30 when virtual interface T6is in use.

The eNB 20 sends Release RRC Connection to the UE 10, if there is a RRCConnection (step S63).

4. Changes to Current Network Element: 4.1. Changes to eNB:

Need to support new interface T6, new protocol, need to interact withMME for MTC-IWF information, verify if the message carries SD,(optionally) perform authorization on UE.

4.2. Changes to HSS

HSS will query MME about serving eNB information and provide it toMTC-IWF at initial phase.

Next, configuration examples of the MTC-IWF 50, the MME 30, the HSS 40,the eNB 20, and the UE 10 will be described with reference to FIGS. 11to 15. Note that in the following explanation, there will be describedonly elements which specific to this exemplary embodiment. However, itwill be understood that the MTC-IWF 50, the MME 30, the HSS 40, the eNB20, and the UE 10 also include elements for functioning as typicalMTC-IWF, MME, HSS, eNB and UE, respectively.

As show in FIG. 11, the MTC-IWF 50 includes an establishment unit 51 anda transmission unit 52. The establishment unit 51 establishes theabove-mentioned T6 connection to the eNB 20. Upon establishing the T6connection, the establishment unit 51 acquires the Serving NodeInformation from the MME 30 or the HSS 40. Through the T6 connection,the transmission unit 52 transmits the above-mentioned MTC devicetrigger message and Small Data Transmission message between the UE 10and the SCS 60. Note that these units 51 and 52 are mutually connectedwith each other through a bus or the like. These units 51 and 52 can beconfigured by, for example, transceivers which respectively conductcommunication with the eNB 20, the MME 30, the HSS 40 and the SCS 60,and a controller such as a CPU (Central Processing Unit) which controlsthese transceivers.

As show in FIG. 12, the MME 30 includes a transfer unit 31 and a sendunit 32. Over the virtual interface T6, the transfer unit 31transparently transfers the MTC device trigger message and the SmallData Transmission message between the eNB 20 and the MTC-IWF 50. Thesend unit 32 sends the Serving Node Information directly to the MTC-IWF50, or through the HSS 40. Note that these units 31 and 32 are mutuallyconnected with each other through a bus or the like. These units 31 and32 can be configured by, for example, transceivers which respectivelyconduct communication with the eNB 20, the HSS 40 and the MTC-IWF 50,and a controller such as a CPU which controls these transceivers.

As shown in FIG. 13, the HSS 40 includes a request unit 41 and a sendunit 42. The request unit 41 requests the Serving Node Information fromthe MME 30. The send unit 42 sends the Serving Node Information to theMTC-IWF 50. Note that these units 41 and 42 are mutually connected witheach other through a bus or the like. These units 41 and 42 can beconfigured by, for example, transceivers which respectively conductcommunication with the MME 30 and the MTC-IWF 50, and a controller suchas a CPU which controls these transceivers.

As shown in FIG. 14, the eNB 20 includes a transceiving unit 21. Throughthe T6 connection, the transceiving unit 21 transceives the MTC devicetrigger message and the Small Data Transmission message between the eNB20 and the MTC-IWF 50. Further, the transceiving unit 21 retrieves therouting information from the MME 30. Furthermore, the transceiving unit21 receives, on the SRB0, the MO Small Data Transmission message fromthe UE 10. This unit 21 can be configured by, for example, transceiverswhich respectively conduct communication with the UE 10, the MME 30 andthe MTC-IWF 50, and a controller such as a CPU which controls thesetransceivers.

As shown in FIG. 15, the UE 10 includes a send unit 11. The send unit 11sends, on the SRB0, the MO Small Data Transmission message to the eNB20. This unit 11 can be configured by, for example, a transceiver whichconducts communication with the eNB 20, and a controller such as a CPUwhich controls this transceiver.

Based on the above description, the following document will be proposedto 3GPP.

Abstract of the Contribution:

This document presents clarification text for the editor's notes in TR33.868, Section 5.7.4.4.3 MTC-based solution. Proposal is to remove theeditor's notes replacing them with the clarification text.

1 Discussion

(1) Editor's Note: The impact to MME is FFS (For Further Study) whenterminating the security in the IWF and MME receives unprotected NASmessage carrying small data.

In MTC-IWF based solution, when MME receives a NAS message carryingSmall Data (SD), it does the following,

1) Check if the NAS message carries SD.

2) If YES, forward the SD to MTC-IWF and act on the NAS message asdefined in TS 33.401.

If NO, act on the NAS message as defined in TS 33.401.

For any NAS based SD transmission solution, the above two steps showthat on top of current functions, the MME will have to (1) check whethera NAS message carries SD and (2) forward the SD to the MTC-IWF. When NASsecurity is required, the MME has to carry the burden of integrity andconfidentiality protection as well.

Two threats are possible to MME due to small data transmission (SDT):

1) Fake SD is received from

-   -   a. A UE that is authorized to send SD    -   b. A UE that is not authorized to send SD

2) Large amount of SDs are received from UEs.

These threats are valid for any NAS based solutions. Thus unprotectedNAS messages carrying SD does not cause extra impact to MME. In MTC-IWFbased solution the check for above threats is carried at MTC-IWF whilethe MME only forwards the SD to MTC-IWF.

Therefore the impact to MME is that it should verify whether the NASmessage carries SD. This impact is valid for all NAS based solutions.

(2) Editor's Note: Details including confidentiality and integrityprotection of the security protocols between the UE and the MTC-IWFshould be given.

FIG. 16 depicts the protocol stack for MTC-IWF based solution in moredetail.

The protocol between UE and MTC-IWF can be based on PDCP (Packet DataConvergence Protocol). PDCP provides both ciphering, deciphering,integrity protection and integrity verification (as defined in [TS36.323]) which can be re-used. MTC-IWF can be configured with the samealgorithms that UE has.

FIG. 17 shows the packet format for SD that is based on the formatdefined in [TS 36.323].

SN (Sequence Number) can be used to prevent replay attack. KSI (Key SetIdentifier) is a key identifier of subkeys for UE and MTC-IWF todetermine the key to be used for small data transmission protection.MAC-I (Message Authentication Code for Integrity) is computed by theintegrity subkey.

2 Proposal

We propose SA3 to approve the following change to TR 33.868.

5.7.4.4.3 Solution Overview

The solution consists of 1) Authentication and Key Agreement (AKA).During this procedure, HSS derives a master key K_iwf and sends it toMTC-IWF. 2) keys negotiation and establishment using a new Security ModeCommand (SMC) procedure carried between UE and MTC-IWF—this newprocedure can ride on NAS SMC. As a result of this procedure, UE andMTC-IWF share the same K_iwf and subkeys for confidentiality andintegrity protection. 3) SD (both mobile originated, MO, and mobileterminated, MT) and trigger transmission: the transmission can ride onpackets that do not need NAS security as per current specification, withrecognition of such data is being carried, NAS security can be omitted.In the following section we propose the detailed solution.

5.7.4.4.4.4 Protocol Between UE and MTC-IWF

The IWF protocol is between NAS and application layer protocol for MTC,it spans between UE and MTC-IWF and can be transparent to MME/SGSN/MSC.For the protocol between MME and MTC-IWF, the T5-AP defined in clause5.1.1.3.3 TR 23.887 [26] can be used.

FIG. 16 illustrates the protocol stack.

The protocol between UE and MTC-IWF can be based on PDCP.

PDCP provides both ciphering, deciphering, integrity protection andintegrity verification (as defined in [TS 36.323]) which can be re-used.MTC-IWF can be configured with the same algorithms that UE has.

FIG. 17 shows the packet format for SD that is based on the formatdefined in [TS 36.323].

SN can be used to prevent replay attack. KSI is a key identifier ofsubkeys for UE and MTC-IWF to determine the key to be used for smalldata transmission protection. MAC-I is computed by the integrity subkey.

5.7.6.3.2 Impacts to Existing System

The proposed solution requires support from HSS, MTC-IWF and UE It hasthe following impacts:

-   -   New keys derivation at UE and HSS, new keys handling in UE and        MTC-IWF.    -   Needs an indicator of small data/trigger transmission to provide        message type.    -   Change to NAS protocol messages for AKA and SMC.    -   MME needs to verify whether the NAS message carries SD.

Note: This impact is valid for all NAS based solutions.

Note that the present invention is not limited to the above-mentionedexemplary embodiment, and it is obvious that various modifications canbe made by those of ordinary skill in the art based on the recitation ofthe claims.

The whole or part of the exemplary embodiment disclosed above can bedescribed as, but not limited to, the following supplementary notes.

(Supplementary Note 1)

New interface is created between eNB and MTC-IWF SMC (Security ModeCommand), named T6.

(Supplementary Note 2)

Device trigger and Small data transmission are delivered over T6 betweeneNB and MTC-IWF.

(Supplementary Note 3)

HSS requests serving eNB information from MME and sends it to MTC-IWF inSubscriber Information Response.

(Supplementary Note 4)

MME informs the eNB change by sending Serving Node Information Update toMTC-IWF at the change happens.

(Supplementary Note 5)

eNB retrieves serving MTC-IWF information from MME for MO small datatransmission.

(Supplementary Note 6)

eNB pages the MTC UE locally without MME involvement before submittingthe small data, especially beneficial for low mobility MTC UEs.

(Supplementary Note 7)

UE sends MO small data or MT small data confirm on SRB0, thus there isno need to have RRC Connection Establishment so as to reduce RRCsignaling.

(Supplementary Note 8)

MTC-IWF sends the integrity session key, which it shares with UE, toeNB.

(Supplementary Note 9)

A node that serves as an entering point to a core network for a serviceprovider, the node comprising:

establishment means for establishing a connection to a base station; and

transmission means for transmitting, by use of the connection, trafficbetween the service provider and a UE (User Equipment) that attaches tothe core network through the base station,

wherein the establishment means is configured to establish as theconnection:

a first connection for directly transceiving messages between the nodeand the base station; or

a second connection for transparently transceiving the messages througha different node that is placed within the core network and hasestablished a different secure connection to the base station.

(Supplementary Note 10)

The node according to Supplementary note 9, wherein the establishmentmeans is configured to acquire, from the different node, information onthe base station that is necessary for establishing the first or secondconnection.

(Supplementary Note 11)

The node according to Supplementary note 10,

wherein the different node comprises an MME (Mobility ManagementEntity),

wherein the establishment means is configured to acquire the informationfrom the MME through an HSS (Home Subscriber Server).

(Supplementary Note 12)

The node according to Supplementary note 10,

wherein the different node comprises an MME,

wherein the establishment means is configured to receive the informationfrom the MME, each time the UE changes a base station to which the UEattaches.

(Supplementary Note 13)

The node according to any one of Supplementary notes 9 to 12, whereinthe transmission means is configured to transmit, as the messages, atleast one of an MTC (Machine-Type-Communication) device trigger messageand a Small Data Transmission message.

(Supplementary Note 14)

A node that manages mobility of a UE attaching to a core network througha base station, the node comprising:

transfer means for transparently transferring messages between the basestation and a different node, the different node serving as an enteringpoint to the core network for a service provider and transmittingtraffic between the service provider and the UE.

(Supplementary Note 15)

The node according to Supplementary note 14, further comprising:

send means for sending information on the base station to the differentnode.

(Supplementary Note 16)

The node according to Supplementary note 15, wherein the send means isconfigured to send the information through an HSS (Home SubscriberServer).

(Supplementary Note 17)

The node according to Supplementary note 15, wherein the send means isconfigured to send the information each time the UE changes a basestation to which the UE attaches.

(Supplementary Note 18)

The node according to Supplementary note 15, wherein the send means isconfigured to:

page the UE at the request of the different node; and

include the information in a response to the request.

(Supplementary Note 19)

The node according to any one of Supplementary notes 14 to 18,

wherein the different node comprises an MTC-IWF (MTC Inter-WorkingFunction),

wherein the transfer means is configured to transparently forward, asthe messages, at least one of an MTC device trigger message and a SmallData Transmission message.

(Supplementary Note 20)

A node that manages subscription information on a UE attaching to a corenetwork through a base station, the node comprising:

request means for requesting information on the base station from afirst node that manages mobility of the UE; and

send means for sending the information to a second node that serves asan entering point to the core network for a service provider and thattransmits traffic between the service provider and the UE.

(Supplementary Note 21)

A base station comprising:

transceiving means for transceiving messages between the base stationand a node through a first connection or a second connection to thenode, the node serving as an entering point to a core network for aservice provider and transmitting traffic between the service providerand a UE that attaches to the core network through the base station, thefirst connection being for directly transceiving the messages, thesecond connection being for transparently transceiving the messagesthrough a different node that is placed within the core network and hasestablished a different secure connection to the base station.

(Supplementary Note 22)

The base station according to Supplementary note 21, wherein thetransceiving means is configured to retrieve, from the different node,information that is necessary for routing a message received from the UEto the node through the first or second connection.

(Supplementary Note 23)

The base station according to Supplementary note 21 or 22, wherein thetransceiving means is configured to receive, on a SRB0 (Signalling RadioBearer 0), from the UE a message to be transmitted to the node throughthe first or second connection.

(Supplementary Note 24)

The base station according to any one of Supplementary notes 21 to 23,

wherein the different node comprises an MTC-IWF,

wherein the transceiving means is configured to transceive, as themessages, at least one of an MTC device trigger message and a Small DataTransmission message.

(Supplementary Note 25)

A UE that attaches to a core network through a base station and thatcommunicates with a service provider, the UE comprising:

send means for sending, on a SRB0, to the base station a message to betransmitted to the service provider through the core network.

(Supplementary Note 26)

The UE according to Supplementary note 25,

wherein the service provider comprises an SCS (Service CapabilityServer),

wherein the send means is configured to send, as the message, a SmallData Transmission message.

(Supplementary Note 27)

A communication system comprising:

a base station that connects a UE to a core network; and

a node that serves as an entering point to the core network for aservice provider and that transmits traffic between the service providerand the UE,

wherein the node establishes as a connection to the base station:

a first connection for directly transceiving messages between the nodeand the base station; or

a second connection for transparently transceiving the messages througha different node that is placed within the core network and hasestablished a different secure connection to the base station.

(Supplementary Note 28)

A method of controlling operation in a node that serves as an enteringpoint to a core network for a service provider, the method comprising:

establishing a connection to a base station; and

transmitting, by use of the connection, traffic between the serviceprovider and a UE that attaches to the core network through the basestation,

wherein as the connection, one of following connections is established:

a first connection for directly transceiving messages between the nodeand the base station; or

a second connection for transparently transceiving the messages througha different node that is placed within the core network and hasestablished a different secure connection to the base station.

(Supplementary Note 29)

A method of controlling operations in a node that manages mobility of aUE attaching to a core network through a base station, the methodcomprising:

transparently transferring messages between the base station and adifferent node, the different node serving as an entering point to thecore network for a service provider and transmitting traffic between theservice provider and the UE.

(Supplementary Note 30)

A method of controlling operations in a node that manages subscriptioninformation on a UE attaching to a core network through a base station,the method comprising:

requesting information on the base station from a first node thatmanages mobility of the UE; and

sending the information to a second node that serves as an enteringpoint to the core network for a service provider and that transmitstraffic between the service provider and the UE.

(Supplementary Note 31)

A method of controlling operations in a base station, the methodcomprising:

transceiving messages between the base station and a node through afirst connection or a second connection to the node, the node serving asan entering point to a core network for a service provider andtransmitting traffic between the service provider and a UE that attachesto the core network through the base station, the first connection beingfor directly transceiving the messages, the second connection being fortransceiving the messages transparently through a different node that isplaced within the core network and has established a different secureconnection to the base station.

(Supplementary Note 32)

A method of controlling operations in a UE that attaches to a corenetwork through a base station and that communicates with a serviceprovider, the method comprising:

sending, on a radio bearer shared with one or more different UEs, to thebase station a message to be transmitted to the service provider throughthe core network.

REFERENCE SIGNS LIST

-   10 UE (MTC UE)-   11, 32, 42 SEND UNIT-   20 eNB-   21 TRANSCEIVING UNIT-   30 MME/SGSN-   31 TRANSFER UNIT-   40 HSS-   41 REQUEST UNIT-   50 MTC-IWF-   51 ESTABLISHMENT UNIT-   52 TRANSMISSION UNIT-   50H H-MTC-IWF-   50V V-MTC-IWF-   60 SCS

1. A first node in a mobile communication system, the first nodecomprising: a processor; and a memory having stored thereon a set ofinstructions executable by the processor, wherein upon execution of theinstructions the processor causes the first node to: establish aconnection between the first node and a second node, receive small datafrom the second node using first information indicating the small data,the second node receiving, from a UE (User Equipment), a messageincluding the small data, and send a release request to the second nodeso that the second node deletes second information for the small datawhen the first node determines a release of the connection.
 2. The firstnode of claim 1, wherein the UE sends the message to the second nodewith integrity and confidentiality protection.
 3. The first node ofclaim 1, wherein in roaming case, the first node is located in HPLMN(Home PLMN (Public Land Mobile Network)) and a third node is located inVPLMN (Visited PLMN (Public Land Mobile Network)) for inter-connectionwith the first node, and the third node connects to the second node. 4.The first node of claim 1, wherein the first node comprises a MTC-IWF(Machine-Type-Communication Inter-Working Function).
 5. The first nodeof claim 1, wherein the second node comprises an eNB (evolved NodeB). 6.A method of a first node in a mobile communication system, the methodcomprising: establishing a connection between the first node and asecond node; receiving small data from the second node using firstinformation indicating the small data, the second node receiving, from aUE (User Equipment), a message including the small data; and sending arelease request to the second node so that the second node deletessecond information for the small data when the first node determines arelease of the connection.
 7. The method of claim 6, wherein the UEsends the message to the second node with integrity and confidentialityprotection.
 8. The method of claim 6, wherein in roaming case, the firstnode is located in HPLMN (Home PLMN (Public Land Mobile Network)) and athird node is located in VPLMN (Visited PLMN (Public Land MobileNetwork)) for inter-connection with the first node, and the third nodeconnects to the second node.
 9. The method of claim 6, wherein the firstnode comprises a MTC-IWF (Machine-Type-Communication Inter-WorkingFunction).
 10. The method of claim 6, wherein the second node comprisesan eNB (evolved NodeB).
 11. A UE (User Equipment) in a mobilecommunication system, the UE comprising: a processor; and a memoryhaving stored thereon a set of instructions executable by the processor,wherein upon execution of the instructions the processor causes the UEto: send, to a second node, a message including small data, the secondnode sending the small data to a first node using first informationindicating the small data; and receive a response from the second nodeafter the first node sends a release request of a connection between thefirst node and the second node to the second node so that the secondnode deletes second information for the small data.
 12. The UE of claim11, wherein the UE sends the message to the second node with integrityand confidentiality protection.
 13. The UE of claim 11, wherein inroaming case, the first node is located in HPLMN (Home PLMN (Public LandMobile Network)) and a third node is located in VPLMN (Visited PLMN(Public Land Mobile Network)) for inter-connection with the first node,and the third node connects to the second node.
 14. The UE of claim 11,wherein the first node comprises a MTC-IWF (Machine-Type-CommunicationInter-Working Function).
 15. The UE of claim 11, wherein the second nodecomprises an eNB (evolved NodeB).
 16. A method of a UE (User Equipment)in a mobile communication system, the method comprising: sending, to asecond node, a message including small data, the second node sending thesmall data to a first node using first information indicating the smalldata; and receiving a response from the second node after the first nodesends a release request of a connection between the first node and thesecond node to the second node so that the second node deletes secondinformation for the small data.
 17. The method of claim 16, wherein theUE sends the message to the second node with integrity andconfidentiality protection.
 18. The method of claim 16, wherein inroaming case, the first node is located in HPLMN (Home PLMN (Public LandMobile Network)) and a third node is located in VPLMN (Visited PLMN(Public Land Mobile Network)) for inter-connection with the first node,and the third node connects to the second node.
 19. The method of claim16, wherein the first node comprises a MTC-IWF(Machine-Type-Communication Inter-Working Function).
 20. The method ofclaim 16, wherein the second node comprises an eNB (evolved NodeB).